Some systems require and/or would benefit from low-peak-to-average power ratio (PAPR) transmission. This may be particularly important for massive Internet of Things (IoT) applications in which the transmitters are machine type communications (MTC) transmitters that are inexpensive and do not have a high power amplifier capability.
SCMA provides good performance and flexibility for massive connectivity required for uplink grant-free transmission suitable for massive IoT applications. SCMA provides a good tradeoff in terms of performance, complexity and massive connectivity. Low-PAPR SCMA codebooks have been proposed but these only work for very narrow-band transmission. Low PAPR SCMA codebooks contain only one non-zero component in each of the codewords associated to the same layer. The tone hopping feature of the codebook allows for constant amplitude on OFDM. That is only true for one SCMA spreading block per OFDM symbol. Multiple blocks will result in higher PAPR.